﻿    <p>
      An <em>IfcTaskType</em> defines a
      particular type of task that may be specified for use
      within a work control.
    </p>
    <blockquote class="history">
HISTORY&nbsp; New entity in IFC4
    </blockquote>
    <p>
      An <em>IfcTaskType</em> provides for all forms of types of
      task that may be specified. It is a reference definition 
      for a unit of work that may be broken down into (a sequence of) 
      subtasks. Please note that a reference definition can not be 
      part of a workflow definition, i.e. <em>IfcTaskType</em> 
      instances define the most abstract level of a reference process 
      without dependencies to other reference processes.
    </p>
    <p>
      Usage of <em>IfcTaskType</em> defines the parameters for one
      or more occurrences of <em>IfcTask</em>. Parameters may be
      specified through property sets that may be enumerated in
      the <em>IfcTaskTypeEnum</em> data type or through explict
      attributes of <em>IfcTaskType</em>. Task occurrences
      (<em>IfcTask</em> entities) are linked to the task type
      through the <em>IfcRelDefinesByType</em> relationship.
    </p>
    <p>Figure 2 shows the definition of a task type that is part
      of a task template library. Please note that in this
      example the task type is further subdivided into tasks that
      define task times (for example, duration) and/or a task sequence.
    </p>
<table><tr><td><img src="../../../figures/ifctasktype_instantiation_diagram.png"
      alt="task type instantiation diagram" border="0"></td></tr>
<tr><td><p class="figure">Figure 2 &mdash; Task type relationships</p></td></tr>
</table>